This invention relates to optical memory methods and systems. More specifically, this invention relates to the use of electron trapping materials in such methods and systems.
Optical techniques for information storage permit rugged, removable media to carry 10 to 20 times more data per platter than the best available fixed inductive magnetic media and 100 times more than the best removable media. After years of research and development, optical memory drives and media have recently begun commercialization. These optical memories have generally been based upon laser video disc technology, a particular type of read-only memory.
As used herein, an "optical memory" is a memory wherein the value of data is read depending on "optical energy" (defined herein as visible light, infrared, or ultraviolet radiation) from the memory.
Although the analog read-only video disc systems have been generally useful, such systems have been subject to several disadvantages. Specifically, these systems rely upon a pattern etched within the laser disc and are not generally subject to reprogramming. The initial "programming" of the laser disc requires a generally high power laser source to "burn" the pattern into the disc, although additional copies may be made by photolithography.
Various optical memory developments are described in "SPECIAL REPORT: THE OPTIONS MULTIPLY IN MASS STORAGE" beginning at Page 28 of the May 19, 1986 Electronics, copyright 1986, McGraw-Hill, Inc., which magazine article is hereby incorporated by references.
Among current optical memory proposals and non-optical memory designs numerous disadvantages such as high access time, costly construction materials, low density of storage, low speed of programming and/or access, high error rates, lack of erasability, and high power requirements are common. Additionally, some known memory systems require a "refresh" step upon access of the memory or every so often to avoid having the memory lose data. That is, the data is lost from the memory upon access or over time such that "refresh" methods and techniques must be used. A further disadvantage of numerous prior memory systems is that they are volatile in that they lose their data upon a loss of power.